METEOROLOGY XTsD ALLIED SUBJECTS. 261 



Dr. "Wagoner lias devised an apparatus for recording certain features 

 of oartliquake shocks, namely: The time, the greatest horizontal motion, 

 both amount and direction. B^mng the first three months of its work- 

 ing, it recorded eleven earthquakes at Tokio, Japan, and this expe- 

 rience would seem to demonstrate the practical value of the appaj-atus. 

 The horizontal movement of a point on the earth's surface is about 

 O'^^.OS (5^ inch) in the case of earthquakes that are scarcely per- 

 ceptible; but is O^'^.S (-3^ inch) for earthquakes ot moderate intensity. 

 [Z. 0. G. ilf., p. 102, Vol. XV.) 



IV. — CHEMICAX, AND rHYSICAL PROPERTIES OF THE ATMOSPHERE. 



Jolly has investigated the variability of the chemical constitution of 

 the atmosphere by two methods, both by the balance and eudiometer. 

 His published measures were made from 1875 to 1877, and give the fol- 

 lowing results: The percentage of oxygen computed for the extreme 

 cases was 20.9G5 at the maximum, and 20.477 for the minimum, or a 

 variabOity of -^ of one per cent. The polar current, if it continues for 

 a season, brings a higher percentage of oxygen, and the equatorial cur- 

 rent a lower percentage. The eudiometric method was used as a check 

 upon these results, and gave a maximum of 21.01 per cent, and a mini- 

 mum of 20.53 per cent. The proposition as to the constancy of the con- 

 stitution of the air is therefore untenable; and Eegnault suspected 

 rightly when he declared it deceptive to so accept the air as a unit for 

 the specific gravity of gases. . 



The important question now arises. What are the variations in the con- 

 stitution of the air, and what their causes ? Jolly believes that the smaller 

 percentage of oxygen in the equatorial current arises from the fact that 

 in the tropics and subtropics, in spite of the greater vegetation, the ox- 

 idation exceeds the reduction, while in the Polar regions the contrary 

 is the case. {Z. 0. G. M., XIV, 1879, p. 228.) 



Soret has communicated some preliminary results from an incomplete 

 investigation into the law of radiation at high temperatures, which inves- 

 tigation had as its object to show how far in such cases the Diilong-Petit 

 law deviates from the truth. A platinum wire, measuring 0.31 mil- 

 limeters in diameter and 385 millimeters long, is, by means of an electro- 

 dynamic machine, heated to the melting point. This machine is driven 

 by a hydraulic motor whose normal strength is 4 horse-power, or a work- 

 ing force of 18,000 kilogrammeters. This work is equivak'ut to an in- 

 crease of temperature of 42.3 calories. If, now, we assume that the whole 

 work in the electric current is converted into heat which is applied to 

 the heating of the i>latiuum wire, then the latter can in one minute 

 receive not more than 42.3 calories. 



But on the trial the platinum wire melted in a few seconds and broke 

 into pieces — the study of which showel that the wire was melted through- 

 out its whole length. Therefore the "5\~ire had attained the temperature 

 of melting platinum in every part, which temperature must have been 



